Those odd groups "F9/181/015/688" are usually only used "in house" by the met people. They are used to indicate such things as quality of the data or the sensors themselves and are usually edited out automatically before dissemination to users outside of BoM. Sometimes those groups can actually take up more space than the metar/speci itself!
The "/" figures are inserted when data is not available; either the sensors aren't working or else there isn't a person on duty to fill in the gaps.
Hope that helps.
Cheers,
Cn